Pesq. Vet. Bras. 33(3):291-298, março 2013 291 RESUMO.-Avaliou-se a utilização da vacina Escherichia coli J5, na imunização de vacas leiteiras, para prevenção e controle da mastite causada por E. coli através da aná-lise da prevalência das infecções intramamárias (IMM) no pós-parto, ocorrência e intensidade dos casos clínicos de mastite nos primeiros 100 dias de lactação, influência na We evaluated the use of Escherichia coli J5 vaccine immunization in dairy cows for the prevention and control of mastitis caused by E. coli. Were analyzed the prevalence of postpartum intramammary infections (IMM), occurrence and severity of clinical cases of mastitis in the first 100 days of lactation, influence on somatic cell count (SCC) and milk production. The experimental group consisted of 187 animals that were divided into two groups, vaccinated and unvaccinated cows. Immunizations occurred 60 days before calving, 30 days before calving and the first week postpartum. On the day of drying and seven days after birth, samples were collected for microbiological diagnosis of mastitis pathogens. The occurrence of clinical cases was verified by testing during the milking and data was recorded related to the intensity and duration. Samples were collected monthly starting at day ten of lactation to evaluate the CCS. Milk production was recorded monthly for the first 100 days of lactation. It was found in the vaccinated group reduction in the prevalence of E. coli in the postpartum period, the occurrence of clinical cases of E. coli in the first 100 days of lactation as well the intensity of these clinical cases. There were no statistically significant differences in CCS, however vaccinated cows had higher milk production, compared to unvaccinated cows. Vaccination with E. coli J5 was effective in reducing the prevalence of intramammary infections (IMM) at calving, occurrence and intensity of clinical cases and an increase in milk production in the first 100 days of lactation. Utilização da vacina